The CDC immunization schedule is based on recommendations developed by the Advisory Committee on Immunization Practices (ACIP), a federal advisory committee that was established in 1964 by the US Surgeon General. The ACIP has 15 voting members, including 14 medical and/or public health experts and one consumer representative, as well as a chairperson. The ACIP has non-voting members from other government agencies and liaison representatives from select professional healthcare organizations, including the American Academy of Pediatrics and the American Academy of Family Physicians. Interested persons apply to serve as a voting member on the committee and are screened for conflicts of interest and are selected for membership for four-year terms by the Secretary of the US Department of Health and Human Services. The ACIP meets three times each year at CDC in Atlanta, Georgia. The meetings are open to the public and are available for viewing as online webcasts.

The ACIP only reviews vaccines that have been licensed by the Food and Drug Administration (FDA). The information considered by the ACIP in making its immunization recommendations includes data regarding the vaccine safety and effectiveness (at specific ages), the severity of the disease to be prevented, the timing of the disease in children and the number of children who would get the disease if they did not get the vaccine.

The background work of the ACIP is done by its members throughout the year in work groups that gather new information about existing vaccines as it becomes available and gather data about new vaccines as they are going through the FDA approval stages. The work groups use a specific framework (GRADE or “Grading of Recommendations Assessment, Development and Evaluation”) in performing their review work in which they “systematically assess the type or quality of evidence about a vaccine’s expected health impacts, and the balance of health benefits and risks, along with the values and preferences of persons affected, and health economic analyses.” The work groups present their scientific information and suggested recommendations at ACIP meetings for voting and approval by the ACIP. The ACIP recommendations include the age(s) for vaccine to be administered and the number of doses and timing of doses, as well as precautions and contraindications (circumstances when the vaccine should not be given to certain individuals).

After the ACIP votes on and approves the immunization schedule, the recommendations are forwarded to the CDC Director for approval. After approval by the CDC Director and the US Department of Health and Human Services, the immunization schedule represents the CDC official recommendation and is published in the CDC’s Morbidity and Mortality Weekly Report (MMWR).

“The IOM committee uncovered no evidence of major safety concerns associated with adherence to the childhood immunization schedule, which should help to reassure a diverse group of stakeholders. Indeed, rather than exposing children to harm, following the complete childhood immunization schedule is strongly associated with reducing vaccine-preventable diseases.”

The CDC describes current vaccines as “the safest, most effective vaccine supply in its history.” There are several different ways in which vaccine safety, including side effects, and vaccine effectiveness are continually monitored. The first method is oversight by the FDA. Before the FDA approves a vaccine for use in the United States, the FDA evaluates the results of vaccine safety and effectiveness studies. FDA also inspects vaccine manufacturing sites to ensure that its strict manufacturing guidelines are being followed.

Less common side effects may be identified through these ongoing vaccine monitoring systems. In addition, ongoing vaccines research studies provide additional data regarding the safety and effectiveness of the vaccines. If additional information is identified during the monitoring or through ongoing vaccine research, the ACIP review process would take this into account when determining if its existing vaccine recommendations should be changed.

The CDC has identified common concerns regarding vaccine safety and has information to address them on its website. For example, the CDC has information on its website addressing general concerns about vaccines, such as about the impact of substances added to vaccines to improve response to the vaccines (adjuvants), concerns related to autism and sudden infant death syndrome, as well as concerns about specific vaccines.

Finally, in addition to the CDC recommendations at the national level, each state sets the requirements for its schools and child care facilities in terms of the required immunizations.